High-frequency apparatus



Patented May 4, 1943 UNETED ear or Flor. I

HIGE-FREQUENCY APPARATUS Pennsylvania Application August 13, 1940, Serial No. 352,411

11 Claims.

My invention relates to electrical harmonic oscillators or amplifiers for very short wave lengths, of the order of 10 centimeters or less, or in the range from one centimeter to one meter, more or less.

The principal object of my invention is to provide means for utilizing a conductor-ensheathed hollow-body resonator, or a plurality of such resonators, with means for causing the same to oscillate at a harmonic resonating-frequency at some multiple of the fundamental or lowest resonating-frequency, in combination with'coupling-circuit means for coupling the internal oscillations within said resonator or resonators to some external device.

A more specific object of my invention is to utilize such harmonically-energized hollow-conductor resonators in a type of short-wave oscillation-generator or amplifier utilizing an electronstream as a source of electrical energy which is modulated by the resonator-means, and which is finally utilized to deliver amplified high-frequency energy for exciting another portion of either the same resonator-means or a separate resonator-means.

The further object of my invention is to provide hollow-conductor resonator-means which are physically of a considerably larger dimension thanthe electrical wave length thereof.

In hollow-body resonators operating at their fundamental frequency, the physical dimensions of the resonator vary as the wave length, being approximately of the same length or breadth as the wave length. For very short wave lengths, such as 10 centimeters or less, such resonators would have such small physical dimensions as to make the construction and assembly of the same very difiicult, besides making it extremely difficult to cool such resonators properly, or to obtain an electron-beam which is sharp enough to send sufficient current therethrough, all of which limits the amount of power which can be handled by the device. By operating the resonator so that it oscillates in a harmonic mode, I can build the resonators with dimensions corresponding to a considerably longer wave length, and yet I can maintain oscillations corresponding to some fraction of that wave length, such as a half, or a; quarter, or some other fraction corresponding to any predetermined harmonic mode of oscillation.

With the foregoing and other objects in view,

my invention consists in the apparatus, combinations, systems and methods hereinafter described and claimed, and illustrated in the accompanying drawing, the single figure of which is a very much simplified diagrammatic cross-sectional viewiof an exemplary embodiment of my invention, with a diagrammatic indication ofa'simple illustrative external-circuit means for utilizing the same.

. The illustrated embodiment of myinvention comprises a box-like, or closed cylindrical, metal container 1 whichv is evacuated to. any suitable degree, such as 10- millimeters of mercury, more or less, depending upon the voltage, current, and sharpness of focusing of the electron-beam which will be subsequently described. The container 1 is illustrated as being provided with four spaced transversely arranged metallic partitions 2, 3, A and 5, in such manner that the space .6 enclosed between the first and second partitions 2. and 3 may be utilized as a first hollow-body'r'esonator,

while the space 1 between the third and fourth partitions 4 and 5 may be utilized as'a second hollow-body resonator. r

In accordance with my present invention, the resonator-spaces 6 and 1 are electrically excited so that they will operate at some predetermined harmonic mode of oscillation, or multiple of the fundamental frequency thereof. Various means may be adapted to bring about such a harmonic mode of oscillation, and in its brodest aspects my invention is not limited to any particular means for this purpose. By way of illustration, I have shown the four partitions 2 to 5 as being provided with aligned off-center openings 8, 9, l0 and H, the oiI-center positions of which are chosen to correspond to the desired harmonic mode of oscillation, by assuring that there shall be a loop or antinode in the electric field at these points. I have also illustrated my resonator-combination as comprising means for passing a beam of electrons successively through the four openings 8 l I, such means being illustrated, in its bare essentials, without any .attempt at refinements such as are known in the art. The beam-producing means includes a source of emitting electrons, which is illustrated as a filamentary cathode 13 having leads l4 and I 5 extending outside of the casing through suitable hermetically-tight insulating bushings It. The cathode I3 is disposed in alignment with the partition-openings 8-H, and the electrons emitted therefrom are accelerated by means of a suitable unidirectional source of po tential of the order of from '500 to 5000 volts, more or less, as represented by a variable battery I? which is connected between the grounded casing, at 18, and one of the leads l5 of the cathode I3. The electron-stream, after passing through the openings 8H, is deflected by means of insulated electrode which is supported on an insulator 2| mounted on the inside of the far wall 22 of the casing I, that is, the wall furthest away from the cathode l3. The insulated electrode 20 is preferably made of carbon or other material having a secondary electron-emissivity ratio materially less than unity, and it is designed to fioat at a potential determined by the accumulation of electrons thereon, said potential being almost as great as the negative potential given to the cathode I 3 by the potential-source IT. The object of the floating electrode 20 is to deflect the electron-beam and cause it to spread out, so that it reaches the walls of the casing I, after passing through the last partition 5, in a fan-like member, without 'being concentrated in a single concentrated beam which might tend to burn the casing. The

floating electrode 20 constitutes the subject matter of a copending application of G. L. Tawney, Serial No. 323,935, filed March. 14, 1940. and'assigned. to the Westinghouse Electric 8; Manufacturing. Company.

Suitable external circuit coupling-means should: be associated with the first resonatorspace 6 for exciting the internal oscillations thereof, and I have illustrated such means in the form of. a coupled feedback-means for deriving a certain amount of. energy from the internal oscillations of the second resonator-space l, and

for'supplying the same, in the form of high frequency electrical current, to the internal oscillations of the first resonator-space 6. The illustrated coupled feedback-means includes. a halfloop 23 terminating on the inside of the particonductor 25 which passes, in spaced manner, L

through suitable perforations 26 and 2'! which are provided in the partitions 3 and 4, respectively. The half-loops 23 and 24 are designed to be coupled with portions of the magnetic fields of the internal oscillations of the respective resonator-spaces 6 and l, and determine points at which the magnetic fields are not zero, thus determining, to that extent, the mode of oscillation.

It is necessary to provide some external-circult coupling-means for deriving energy from the internal oscillations of the second oscillatorspace 1, and delivering such amplified high-frequency energy to some external circuit or device. this coupled output-means as comprising a third half-loop member 28 which terminates on the inside of the partition 5-within said second resonator-space I, said third half-loop 28 having a conductor 29 extending therefrom. The conductor 29 passes in spaced, or insulated, fashion through an'opening 30' providedin the partition 5, and is connected to a conductor 3|, which passes out of the casing I, through a suitable vacuum-tight insulating bushing 32. The output-conductor 3| is electrically connected to some device utilizing the high-frequency electrical energy, which may be any suitable device, being illustrated as an antenna 33.

In' operation, the electrons emitted from the cathode [3. are concentrated in a beam, as they pass through the first partition-opening 8, or they. are concentrated or focused by other more elaborate apparatus, such as is known in the art, and which constitutes no essential part of By way of illustration, I have illustrated my present invention, other than suitable beamproducing means are utilized. These electrons are accelerated, or given a substantially uniform velocity, by means of the electrostatic potentialgradient which is established, by the battery l'l, between the first partition 2 and the cathode IS. The electron-stream or beam, in passing through the aligned openings 8 and 9 of the first resonator-space 6, is subjected to a high-frequency electrostatic field or gradient in substantial alignment with the electron-beam, as a result of the hollow-space resonations or oscillations of the hollow-conductor body enclosing said first resonator-space 6, whereby the electrons of the beam are alternately accelerated and retarded, as they pass through the intervening space between the two openings 8 and 9 of this resonatorspace.

After leaving the second opening 9, the electron-stream passes through a certain drift-space in which there is an opportunity for the electrons to become bunched by reason of the velocity-modulation which is imparted to the electron-beam in passing through the first resonator-space 6, said first resonator-space 6 being commonly known as a buncher because of this bunching function. After leaving the drift-space between the second and third partitions 3 and 4, the electron-stream then passes through the partition-openings I0 and H of the second resonator-space l, which is known as a catcher, because the bunches of electrons follow one another in time-spaced pulsations at a high-frequency rate, and give up some of their energy to the second oscillator-space l, or catcher, so as to increase the resonant oscillations in said catcher. After leaving the last wall-opening H of the catcher I the electron-stream passes on into the final compartment of the envelope I, between the partition 5 and the end Wall 22, where the electrons are finally collected on the walls of the container i.

In the illustrated form of embodiment of my invention, a part of the oscillation-energy of the catcher l is returned, by the internal coupling means 24-2523, to the internal oscillations of the buncher 6, so as to increase the magnitude of the resonant oscillations in the buncher 6. This so-called feedback-energy may be either sufiicient to produce sustained oscillations, in which case an oscillation-generator is produced, or it may fall short of this amount, in which case a regenerative amplifier is produced, provided that a suitable external-circuit controlling-input means (not shown) is utilized in connection with the buncher 6. In the illustrated form of embodiment of my invention, the apparatus is utilized as an oscillation-generator for supplying sustained high-frequency oscillations to the antenna 33.

In accordance with my invention, it will be noted that the partition-openings 8-4 I, through which the electron-beam passes, are disposed in off-center relation to the respective oscillating spaces 6 and I, so as to excite these spaces in a harmonic mode of oscillation, so that the electrical wave length of the oscillating energy will be only a predetermined fraction of the fundamental wave length as previously described.

In the illustrated form of embodiment of my invention, the partition-openings 8l l, through which the electron-stream passes, are closed or covered by grids 38, 39, til and 41, respectively. The grids 38-4! ar illustrated schematically as metal-wire screens, but it is to be understood that such illustration is only schematic, as such grids may take any of the Well known forms of grids which are known in the art of electrontubes. I also contemplate that the words grids and openings may be understood as being synonymous with each other, either term implying either a single opening or a plurality of juxtaposed openings.

In the particular form of embodiment of my invention illustrated in the drawing, the two grids 40 and 4| of the catcher I are closer together, in the direction of the electron-stream, than the two grids 38 and 39 of the buncher 6, this construction being brought about by the utilization of short tubes 42 and 43 disposed in the partition-openings l and II of the catcher 1. The purpose of this construction is to increase the sharpness of the response of the catcher I to the bunches of electrons in the bunched electron-stream, and also to prevent the oscillations of the electrostatic field, in the catcher, in alignment with the electron-stream, from over-modulating the velocities of the electrons in said stream or withdrawing so much energy that the electron-velocity is reduced to zero, or even reversed, in said catcher 1.

In normal operation, the amount of heating of the filament I3, and the amount of accelerating-potential of the biasing battery H, are so controlled that the apparatus operates as an oscillation-generator, with sustained oscillations which are delivered to the antenna 33.

While I have illustrated my invention in a single preferred form of embodiment thereof, and while I have reduced such illustration to its very simplest terms, so as to refer to only the bare essentials of my invention, without any of the ordinary refinements of such means as the vacuum-tight construction, the beam-focusing means, or the cooling-means for the container l, I desire it to be understood that such illustration is intended to be only illustrative of the general principles of my invention, as various changes and modifications may be made by those skilled in the art, without departing from its essential principles, particularly in the broader aspects thereof. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A high-frequency hollow-body resonator having a conductor-ensheathed space, in a' combination including excitation-means operative on said resonator at a point in an off-centered relation to its total resonating space for causing said resonator to oscillate at a predetermined harmonic resonating-frequency at some multiple of the fundamental resonating-frequency thereof, and coupling-circuit means for coupling the internal harmonic oscillations within said resonator to some external device.

2. An electron-discharge apparatus comprising an evacuated container; means for producing an electron-beam therein; a modulating beam-coupled means operating on said electron-beam at one region thereof for modulating said beam at a predetermined high-frequency rate; an excited beam-coupled means acted upon by said electronbeam at another region thereof for absorbing high-frequency energy from the modulations of said beam; said beam-coupled means including hollow-body resonator-means having said electron-beam passing in an off-centered relation to the total resonating space of said hollow-body resonator-means to cause the same to oscillate at a predetermined harmonic resonating-frequency at some multiple of the fundamental resonatingfrequency thereof; coupled excitation-means associated with. said hollow-body resonator-means for supplying high-frequency excitation-energy to said modulating beam-coupled means; and coupled output-means associated with said hollow-body resonator-means for deriving high-frequency electrical energy from'said excited beamcoupled means.

3. An electron-discharge apparatus comprising an. evacuated container; means for producing an electron-beam therein; a modulating beam-coupled means operating on said electron-beam at one region thereof for modulatingsaid beam at a predetermined high-frequency rate; an excited beam-coupled means acted upon by said electron-beam at another region thereof for absorbing high-frequency energy from the modulations of said beam; said beam-coupled means including hollow-body resonator-means having said electron-beam passing in an off-centered relation to the total resonating space of said hollow-body resonator-means to cause the same to oscillate at a predetermined harmonic resonating-frequency at some multiple of the fundamental resonatingfrequency thereof; said beam-coupled means being further arranged so as to include a highfrequency power-feedback effect whereby some of the energy of said excited beam-coupled means is fed back to said modulating beam-coupled means; and coupled output-means associated with said hollow-body resonator-means for deriving high-frequency electrical energy from said excited beam-coupled means.

4. An electron-discharge apparatus comprising an evacuated container; means for producing an electron-beam therein; a first hollow-conductor resonator-space means,traversedby said beam, for producing a high-frequency potential-gradient acting longitudinally upon said beam at a predetermined region thereof; means for providing a drift-space to be traversed by said beam after its passage through said predetermined region; and a second hollow-conductor resonatorspace means, traversed by saidbeam issuing from said drift-space, said second hollow-conductor resonator-space means being adapted to be excited at a resonant-frequency by the high-frequencymodulations in said beam and including circuit-means coupled thereto for deriving highfrequency electrical energy from the oscillations therein; characterized by said hollow-conductor resonator-space means including a harmonicexcited conductor-ensheathed resonating-space having excitation means operative thereon at a point in an off-centered relation to the total resonating-space to cause the same to oscillat at a predetermined harmonic resonating-frequency at some multiple of the fundamental resonatingfrequency thereof.

5. An electron-discharge apparatus comprising an evacuated container; means for'producing an electron-beam therein; means, including a source of electrical energy, for producing a unidirectional potential-gradient acting longitudinally upon said beam at a first region thereof; 'a first hollow-conductor resonator-space means, traversed by said beam after it passes said first region, for producing a high-frequency potential-gradient acting longitudinally upon said beam at a second region thereof; means for providing a driftspace to be traversed by said beam after its passage through said second region; and a second hollow-conductor resonator-space means, travmeansibeing adapted to be excited at a resonantfrequency by the high-frequency modulations in said beam and including circuit-means coupled theretofor.deriving-high-frequency electrical energy from the oscillations therein; characterized by said hollow-conductor resonator-space means including a harmonic-excited conductor-ensheathed resonating-space having excitation 'meansoperative thereon at a point in an off-centered-:relation to the total resonating-space to causethe :same 'to oscillate at a predetermined harmonic ;resonating-frequency at some multiple of the :fundamental resonating-frequency there- 6. AIhigh-frequency resonator comprising an evacuated container; means 'for providing a source of emitted electrons therein; at least four successively arranged, spaced grids therein for k providing 'a first intervening space between the first and'second of said four grids, a secondintervening space between-the second and third of said four grids,.and a third intervening space between the-third and fourth'of. said fouri'grids; an includin electron beam producing means, means for producing a potential-gradient somewhere in the space between the electron-source and:the'first of said-four grids, for imparting an initial'velocity to the-electrons and for causing a beam tofu-electrons to flow successively through the four aforesaid grids; hollow-body resonatormeans, including said first and third intervening spaces, for utilizing said first and third intervening spaces, in effect, as parts of a buncher and a catcher, respectively, whereby the electrons of liveringamplified high-frequency energy therefrom; characterized bysaid'electron-beam passing in off-center relation through said hollowbody resonator-means whereby said hollow-body resonator-means resonates at a predetermined harmonic resonating-frequency at some multiple of the fundamental resonating frequency and whereby said electron-stream is velocitymodulated and bunched principally at saidpredetermined harmonic resonating-frequency.

7.-A high-frequency resonator comprising an evacuated container, means for providing a source of emitted electrons therein; at least four successively arranged, spaced grids therein for providing a first intervening space between the first and second of said four grids, asecond intervening space between the second and-third of said four grids, and a third intervening space between the'third and fourthof said four grids; an'electron-:beam-producing means, including 'means for producing a potential-gradient somewhere in the space between the electron-source and the first of said four grids, for imparting an initial velocityto the electrons and for causing a beam of electrons to flow successively through the four aforesaid grids; means for providing,in effect, at least two separate hollow-body resonators, the first of said hollow-body resonators includingsaid ,first intervening space-within its resonating space v aforesaid grids;

ersedibyisaid beam issuingfrom said drift-space, said ,,:second :hollowaconductor resonator-space and operating as abuncher for velocity-modulating the electrons of'sai'd beam, and 'thfiiSfiCOIld of said hollow-body resonators including said third intervening space within its resonatin space and operating as a catcher for increasin its oscillation as a result of the bunched electrons, at least one of said hollow-bodyresonators including its associated intervening space in an off-centered relation to its total resonating space whereby the electron-beam in said intervening space causes said resonator to oscillate at a predetermined harmonic resonating-frequency at some multiple of its fundamental resonating-frequency; coupled excitation-means coupled-to'the internal oscillations within said buncher for supplying high-frequency excitation-energy thereto; and external-circuit coupled output-means coupled to the internal oscillations within said catcher for delivering amplified high-frequency energy therefrom.

8. A high-frequency resonator comprising-an evacuated container; means for providing,,in-effect, two ,conductor-ensheathed hollow resonators therein; oscillation-exciting means for the two resonators, at least one of said oscillation-exciting means being operative on its associated resonator at a point in an off-centered relation to its total-resonating space to cause the same to oscillate at a predetermined harmonic resonating-frequency at some multiple of its fundamental resonating-frequency, the frequencies of the resonant oscillations of the two resonators being substantially identical; said -oscillationexciting means including external-circuit excitation-means coupled to'the internal oscillations within the first resonator for supplying high-frequency excitation-energy thereto; said oscillation-exciting .means further including means for passing an lectron-stream successively through the two resonators whereby the first resonator'operates as aates as a catcher-to derive oscillation-frequency energy'from the bunched electrons, there being an intervening-space wherein the accelerated and decelerated electrons may bunch to some extent before passing through the catcher; and externalcircuit output-means coupled to the internal oscillations of the catcher for delivering amplified high-frequency energy therefrom.

9. A high-frequency resonator comprising an evacuated container; means for providing a source of emitted-electrons therein; at least four successively arranged, spaced grids therein for providing afirst intervening space between the first and second of said four grids, a second intervening space between the second and third of said four grids, and a third intervening space between the thirdand fourth of said four grids; an electron-beameproducing means, including means for producing a potential-gradient somewhere in the space between the electron-source and the first of said four grids, for imparting an initial velocity to the electrons and for causing a beam of electrons to flow successively through the four hollow-body resonator-means, including said first and third interveningspaces, for utilizing said first and third intervening spaces, in efiect, as parts of a buncher and a catcher, respectively, whereby the electrons of said beam are velocity-modulated as a result of the high-frequency resonating electrostatic field in said buncher, and whereby the bunched electrons of said electron-beam yield some of their energy to the high-frequency resonating electrostatic field of said catcher; means for providing a feedback arrangement whereby a part of the high-frequency energy of said catcher is fed back into said buncher; and coupled output-means associated with the catcher for delivering amplified high-frequency energy therefrom; characterized by said electron-beam passing in off-centered relation through said hollow-body resonator-means whereby said hollow-body resonator-means resonates at a predetermined harmonic resonatingfrequency at some multiple of the fundamental resonating-frequency and whereby said electronstream is velocity-modulated and bunched princi pally at said predetermined harmonic resonatingfrequency.

10. A high-frequency resonator comprising an evacuated container, means for providing a source of emitted electrons therein; at least four successively arranged, spaced grids therein for providing a first intervening space between the first and second of said four grids, a second intervening space between the second and third of said four grids, and a third intervening space between the third and fourth of said four grids; an electron-beam-producing means, including means for producing a potential-gradient somewhere in the space between the electron-source and the first of said four grids, for imparting an initial velocity to the electrons and for causing a beam of electrons to flow successively through the four aforesaid grids; means for providing, in effect, at least two separate hollow-body resonators, the first of said hollow-body resonators including said first interventing space within its resonating space and operating as a buncher for velocity-modulating the electrons of said beam, and the second of said hollow-body resonators including said third intervening space within its resonating space and operating as a catcher for increasing its oscillation as a result of the bunched electrons, at least one of said hollow-body resonators including its associated intervening space in an cit-centered relation to its total resonating space whereby the electron-beam in said'intervening space causes said resonator to oscillate at a predetermined harmonic resonating-frequency at some multiple of its fundamental resonating-frequency; means for providing a feedback arrangement whereby a part of the high-frequency energy of said catcher is fed back into said buncher; and coupled output means associated with the catcher for delivering amplified high-frequency energy therefrom.

11. A high-frequency resonator comprising an evacuated container; means for providing, in effect, two conductor-ensheathed hollow resonators therein; intercoupling feedback and oscillationexciting means for the two resonators, at least one of said oscillation-exciting means being operative on its associated resonator at a point in an oil-centered relation to its total resonating space to cause the same to oscillate at a predetermined harmonic resonating-frequency at some multiple of its fundamental resonating-frequency, the frequencies of the resonant oscillations of the two resonators being substantially identical; said intercoupling feedback and oscillation-exciting means including means for passing an electronstream successively through the two resonators whereby the first resonator operates as a buncher to velocity-modulate the electrons of said electron-stream, while the second resonator operates as a catcher to derive oscillation-frequency energy from the bunched electrons, there being an intervening space wherein the accelerated and decelerated electrons may bunch to some extent before passing through the catcher; and coupled output-means associated with the catcher for delivering amplified high-frequency energy therefrom.

ALDEN H. RYAN. 

